Why did this slide drive unit fail on my 35’ four slide Ventana?

[Rich W.]

I have my theory and its a bit concerning but first, what failed? I finally got around to opening this up and found exactly what I expected - a broken gear tooth - it took just one broken tooth on the big gear to render this $804 unit inoperable without manually assisting it on the way in. Interestingly, it moved out without any indication of a problem. See pics:

It certainly wasn’t for lack of lubrication, so what happened? This is a small bedroom ODS slide and I have a theory. I noticed that when this slide starts coming in, the bottom moves in first, putting the slide on an angle (top out of plumb) then the top catches up and it comes in plumb and closes. I also found that I can easily square it up while its coming in by gently pulling on the crown molding at the top of the slide - it easily rocks in and out at the top considerably in the early stage of closing. I don’t know if this is normal and would like to know if other similar units have the same condition. I have an apointment to get all my slides tuned up soon, but back to the issue.

My theory is that when the slide first starts closing, with the bottom moving first and the top sort of hanging out there, it puts a considerable bind on the slide and thus a torque load on the gear box. I don’t know but its all I can think of. The door-side bedroom slide doesn’t have this issue, perhaps because it includes the bed so it has a nice hefty counter weight, or perhaps because the ODS slide is defective or malfunctioning - I just don’t know. To me it feels like something came loose - the slide equivalent of a drawer guide or whatever, but I can see any physical evidence of this.

For now I’ll help it in with a little gentle assist since I can reach the interior top of the slide and the switch at the same time. If anyone has information or experience on this please advise.

 

[Neal]

I've heard of others that went through several motors there was a binding that Newmar had to fix. I've also heard of them aligning slides and maybe yours got out of alignment a little? I don't know. All you can do, if ever going to Newmar, is have it inspected and see what they say.

 

[Rich W.]

I have an apointment later this year and one of the things on the list is for them to do whatever is needed on all the slides, but they all close fairly evenly except for this one hanging out at the top initially. Once its about half way in it aligns vertically and runs in nicely. I can’t recall noticing it before so I’m curious about whether its normal or not. For now I’ll keep assisting it but I don’t like pulling on the crown molding either. I guess I should call Newmar and see if this is a known issue.

It would be nice though if Klauber or Newmar sold that gear for $50; $804 is a little steep for such a small part failure.

 

[RKins]

To me, the small gear does not look like it meshes well with the main gear. Looks like the depth of the teeth is shallow.

 

[Rich W.]

I hadn’t noticed that but I think you’re right. I’ll have to open it back up and take a closer look, but it appears that the big gear is quite worn, with all the teeth squared off, which would explain why it was skipping so much. And all that skipping would lead to shock loading which would explain the broken tooth. It also explains why it needed so much assist to close it - it took far more help than I would expect with just one missing tooth. Also looking at other pics it appears that there is a lot of metal in the grease. Thanks for the observation. When I get home I’ll take another look at it.

 

[Kevin D Pem]

What @Neal said, with a little added.
Insanity is defined as someone doing the same thing over and over, each time expecting a different result.

I never would have bought a vehicle with slides! I am not slamming anyone with my opinion, I just know to much.
No matter how much you pay for an RV it is still the sum of the parts. I would Not expect the same result from a Newell that is designed for each customer, but by far you can look at your rig as a bucket of bolts.
When I look at these pictures, what I see is a pot metal housing with gears with teeth designed for a first stage reduction.
If it were my toy and fixing it was going to cost 800+ I would visit a machine shop and see what it would cost to have them put some real gears in that baby! And fix the problem!!!

 

[Rich W.]

That’s been done successfully Kevin, but by someone with a relative with a machine shop that could produce one-off gears without factoring in cost. Unfortunately he only had one made. I thought about pursuing that approach, but expediency was a priority to get it back in service.

Klauber Machine and Gear makes slide drives for many motorhome makes, not just Newmar, and they also produce elec/gear reduction drive units for many other industries and purposes, and have been doing so for around 70 years, so this is both somewhat unusual and unexpected. And the cost is a result of both stocking/inventory practices and considerable mark-up. If Klauber sold to the public this unit would be about half the cost.

But I suspect the problem is with the slide and that caused the wear, not the drive unit, and I will investigate that. Because of course, I wouldn’t want to keep doing the same thing expecting a different result (obviously one of the reasons I did my own R&R, saved the old unit, opened it up and photographed it, and posted the results of my investigation and follow-up questions here). And for the price difference between my coach and a Newell I could buy over 1,000 of these units, the likelihood of which seems somewhat unlikely.

 

[Kevin D Pem]

That’s been done successfully Kevin, but by someone with a relative with a machine shop that could produce one-off gears without factoring in cost. Unfortunately he only had one made. I thought about pursuing that approach, but expediency was a priority to get it back in service.

Klauber Machine and Gear makes slide drives for many motorhome makes, not just Newmar, and they also produce elec/gear reduction drive units for many other industries and purposes, and have been doing so for around 70 years, so this is both somewhat unusual and unexpected. And the cost is a result of both stocking/inventory practices and considerable mark-up. If Klauber sold to the public this unit would be about half the cost.

But I suspect the problem is with the slide and that caused the wear, not the drive unit, and I will investigate that. Because of course, I wouldn’t want to keep doing the same thing expecting a different result (obviously one of the reasons I did my own R&R, saved the old unit, opened it up and photographed it, and posted the results of my investigation and follow-up questions here). And for the price difference between my coach and a Newell I could buy over 1,000 of these units, the likelihood of which seems somewhat unlikely.

Gear manufacturers have design books. If I still had my fab shop, I would consider designing something for the market. All you really need is center line distance for the gears, and the pitch you desire to select what is needed. Then make the shafts. Don't really think it is much of a job! I no longer have my equipment. Shear pins, with an over rated drive could save owners a bundle over under rated stuff like is used today.
All I was saying about Newell is they are more likely to do it right as they make their own chassis to order.
It's up to you to replace bad under rated equipment when you have to fix something done with the bottom line as the guideline.

I know I am bashing Winnebago, but then that is why my adventure is in the bone yard.

 

[Rich W.]

Yes it’s possible but highly improbable to approach it that way. When I was a kid I worked in a printing shop in SF (McCoy Label, 5th and Bryant) and all the presses were built before 1910 and I was constantly replacing shear pins. But that was a totally different animal. In this case I think gradual but constant wear due to a slide condition issue is the culprit, and if so shear pins wouldn’t help.

So to veer recklessly back on topic, the reason I posted this was to find out if other folks with similar rigs have noticed a similar situation with similar slides (see the trend here?). Anything else falls somewhere along the rhetoric-hyperbole continuum (not even rating as academic) and is not particularly useful. Comparing/contrasting Newells with hydraulic slides is a wonderful example.